Ink jet printers are a well-known and widely used form of printed media production. Ink is fed to an array of micro-processor controlled nozzles on a printhead. As the print head passes over the media, ink is ejected from the array of nozzles to produce an image on the media.
Printer performance depends on factors such as operating cost, print quality, operating speed and ease of use. The mass, frequency and velocity of individual ink drops ejected from the nozzles will affect these performance parameters.
Recently, the array of nozzles has been formed using microelectromechanical systems (MEMS) technology, which have mechanical structures with sub-micron thicknesses. This allows the production of printheads that can rapidly eject ink droplets sized in the picolitre (×10−12 litre) range.
While the microscopic structures of these printheads can provide high speeds and good print quality at relatively low costs, their size makes the nozzles extremely fragile and vulnerable to damage from the slightest contact with fingers, dust or the media substrate. This can make the printheads impractical for many applications where a certain level of robustness is necessary. Furthermore, a damaged nozzle may misdirect the ejected drops or simply fail to eject the ink at all. If the nozzle fails to eject the ink, it can start to bead and affect surrounding nozzles. In time, it may also leak ink onto the printed substrate.
Whether the ejected ink is misdirected or the ink beads on the surface of the printhead, both situations are detrimental to print quality. To address this, the printhead can be provided with an apertured guard over the exterior of the nozzles to avoid damaging contact fingers, dust or the media. However, the guard may also be used to retain misdirected ink droplets or any ink leaked from damaged nozzles. By localizing any ink leakage, the number of nozzles affected can be limited. The guard also prevents misdirected ink droplets from reaching the media.
Unfortunately, the print quality still suffers because it no longer includes the ink from the damaged nozzles. Furthermore, as the containment formation fills with ink, it can still bead on the exterior of the guard to clog the surrounding apertures and or leak onto the media.